DESCRIPTIONThe Sigma 800mm f/5.6 EX DG APO HSM is an apochromatic extreme-telephoto lens with a fast f/5.6 maximum aperture. The ultra-quiet Hyper Sonic Motor (H.S.M.) and Internal Focusing features assist autofocus speed and handling.The improved DG lens design corrects for various aberrations. This lens is specially coated to get the best color balance whilst cutting down on ghosting caused by reflections from the digital image sensor.This lens is ideal for capturing wildlife and sports photography.Powerful and silent Hyper Sonic Motor enables fulltime manual focus overrideSigma's dedicated APO EX 1.4x and 2x teleconverters can be used with this lens, effectively converting it into a 1120mm f/8 or 1600mm f/11 lensTwo Extra-Low Dispersion glass elements reduce chromatic aberration to a minimumA rotating filter holder in the rear of the lens barrel enables easy use of the included circular polarizerLead and arsenic free ecological glass